405Sullivan et al., eds., 2011, Fossil Record 3. New Mexico Museum of Natural History and Science, Bulletin 53.

THE FIRST LAMBEOSAURIN (DINOSAURIA, HADROSAURIDAE,LAMBEOSAURINAE) FROM THE UPPER CRETACEOUS OJO ALAMO FORMATION

(NAASHOIBITO MEMBER), SAN JUAN BASIN, NEW MEXICO

ROBERT M. SULLIVAN1, STEVEN E. JASINSKI1, MERRILEE GUENTHER2 AND SPENCER G. LUCAS3

1 Section of Paleontology and Geology, The State Museum of Pennsylvania, 300 North Street Harrisburg, PA 17120-0024;2 Elmhurst College, 190 Prospect Ave., Elmhurst, IL 60126;

3 New Mexico Museum of Natural History and Science, 1801 Mountain Rd NW, Albuquerque, NM 87104

Abstract—A nearly complete robust left humerus (SMP VP-2263) and right jugal (SMP VP-1534) belonging to alambeosaurin lambeosaurine (= Lambeosaurus + (Corythosaurus + Hypacrosaurus)) dinosaur have been recov-ered from two separate localities in the Naashoibito Member (Ojo Alamo Formation), San Juan Basin, NewMexico. Measurements of the humerus are: length = 550 mm; deltopectoral crest length = 260 mm; deltopectoralwidth = 135 mm. The robust morphology and measurements of the humerus confirm it pertains to a member of thelambeosaurin clade, which we formally establish. The jugal has a maximum rostrocaudal length of 255 mm and ashape that is inconsistent with the jugals of all species of Parasaurolophus. These specimens, which are verysimilar to the humerus and jugal of Corythosaurus and Hypacrosaurus, constitute definite records of lambeosaurinesfrom the Naashoibito Member, despite previous erroneous reports of the occurrence of Parasaurolophus tubicenfrom this horizon. The putative hadrosaurine, NMMNH P-19147, is re-interpreted as a lambeosaurin lambeosaurine,based primarily on the morphology of the pubis. Recovery of additional lambeosaurine material in the NaashoibitoMember lends further support to a pre-Lancian age for this interval and for the Alamo Wash local fauna.

INTRODUCTION

Hadrosaurid dinosaurs from the Ojo Alamo Formation (Sand-stone) have been known for a century. Many of the early records cite thehadrosaurids, and other dinosaurs, as coming from the Ojo Alamos beds(Brown, 1910; Gilmore, 1916; Lehman, 1981, 1985). Only fourhadrosaurid genera have been recognized in the Upper Cretaceous de-posits of the San Juan Basin (Anasazisaurus, Kritosaurus,Naashoibitosaurus and Parasaurolophus). Two of these taxa are stillregarded by some to be of questionable validity (Anasazisaurus andNaashoibitosaurus), and all four genera are from the Kirtland Formation(Williamson, 2000). To complicate matters, two of the San Juan Basinhadrosaurids (Naashoibitosaurus and Parasaurolophus) were originallyreported as coming from the Naashoibito Member, but are now knownto be restricted to the De-na-zin Member of the Kirtland Formation(Williamson, 1998; Williamson and Sullivan, 1998; Sullivan andWilliamson, 1999; Sullivan et al., 2005a, b). The Naashoibito Memberwas previously included in the Kirtland Formation, but is now consid-ered to be part of the overlying Ojo Alamo Formation (Lucas and Sullivan,2000; Sullivan et al., 2005b).

Recently, a number of new lambeosaurines from North Americaand Asia have been documented, and phylogenetically assessed (Godefroitet al., 2001, 2004, 2008; Gates et al., 2007; Prieto-Márquez, 2010a, b).Other studies, most notably that of Guenther (2009), have developedmethods to recognized ontogenetic development of postcranial elementswithin hadrosaurid taxa that help to discriminate lambeosaurine fromhadrosaurine taxa.

In Asia, lambeosaurines are now known from Maastrichtian unitsof Russia (Amurosaurus riabinini [Udurchukan Formation]) (Godefroitet al., 2004; Van Itterbeeck et al., 2005) and northeastern China(Charonosaurus jiayinensis and Sahaliyania elunchunorum [YuliangzeFormation]) (Godefroit et al., 2001, 2008). Although some of these oc-currences are considered late Maastrichtian (~69.2 to 65.5 Ma, as de-fined by Ogg et al., 2004), based on correlation using palynozones, weconsider these correlations to lack precision. Recently, in Europe, a newlambeosaurine Arenysaurus ardevoli, from the lower part of the upperMaastrichtian (normal polarity Chron 30) Tremp Formation of Spain,has been described based on an incomplete skull roof and braincase

(Pereda-Suberbiola et al., 2009). In North America, lambeosaurines areunknown from strata younger than 67 Ma (the base of the Lancian LVA,see below). Although a putative lambeosaurine has been reported fromthe Hell Creek Formation, lambeosaurines are not known from either theLance or upper part of the Hell Creek formations (latest Maastrichtian/Lancian) of the Western Interior. Moreover, lambeosaurine dinosaurs arenot considered a faunal component of the Lancian LVA, which spans65.8-67.61 Ma (latest Maastrichtian). The youngest known North Ameri-can lambeosaurin, Hypacrosaurus altispinus, is from the Horseshoe Can-yon Formation of Alberta, and it comes from the upper part of theformation (unit 4), which is dated at 69-68 Ma. Unit 4 of the HorseshoeCanyon Formation correlates with the Naashoibito Member – both are~ 69 Ma.

Here, we document a humerus (SMP VP-2263) and jugal (SMPVP-1534) of a lambeosaurin lambeosaurine from separate localities in theNaashoibito Member and discuss their biostratigraphic significance. Wealso re-assess the taxonomic assignment of NMNNH P-19147, from theNaashoibito Member, originally interpreted as representing alambeosaurine dinosaur close to either Lambeosaurus or Corythosaurus(Hunt and Lucas, 1991) based on the morphology of the pubis, and, to alesser extent, the scapula. The identity of NMMNH P-19147 had beendismissed by Williamson (2000), who considered it to be an indetermi-nate hadrosaurine.

Institutional abbreviations: NMMNH = New Mexico Mu-seum of Natural History and Science, Albuquerque; SMP = The StateMuseum of Pennsylvania, Harrisburg.

TAXONONOMIC NOTE

We note here that the terms “corythosaur clade” and“parasauroloph clade” were introduced by Chapman and Brett-Surman(1990) as informal clades. The “corythosaur clade” includedCorythosaurus, Hypacrosaurus, Lambeosaurus, and Nipponosaurus.Juvenile specimens of “Procheneosaurus” were also assumed to be mem-bers of this clade. The “parasauroloph clade” included Parasaurolophus,Bactrosaurus and Tsintaosaurus. The taxonomic composition of thesetwo informal clades was changed by Godefroit (2004), who unitedParasaurolophus with Charonosaurus in the “parasauroloph clade”

406and Lambeosaurus with Corythosaurus, Hypacrosaurus and Olorotitanin the “corythosaur clade.” This later clade was elevated to formal usage(“Corythosaurini”) by Evans and Reisz (2007, p. 388), and named theother clade “Parasaurolophini.”

According to Article 37.1 of the International Code of ZoologicalNomenclature (1999) “When a family-group taxon is subdivided, thesubordinate name that contains the taxon that contains the type genus ofthe superior taxon is denoted by the same name the nominotypical name.”Thus, given that “Corythosaurini” is a subdivision (tribe) ofLambeosaurinae coordinate with Parasaurolophini, the proper name ofthe tribe should be Lambeosaurini, not “Corythosaurini.” The followingformal subdivisions of the Lambeosaurinae encompass two clades:Lambeosaurini clade (included taxa are Lambeosaurus, Hypacrosaurus,Olorotitan, Corythosaurus and Velafrons) and the Parasaurolophini clade(included taxa are Parasaurolophus cyrtocristatus, P. walkeri, P. tubicenand Charonosaurus jianyinensis).

MATERIALS AND METHODS

Hadrosaurid postcranial material (jugals, humeri and scapulae) inthe collections of the New Mexico Museum of Natural History andScience in Albuquerque and the State Museum of Pennsylvania wereexamined and compared. Studies characterizing the morphologies of theseelements by Sullivan and Williamson (1999) Sullivan and Bennett (2000),Godefroit et al. (2001, 2004, 2008), Evans and Reisz (2007), Guenther(2009), and Prieto-Márquez (2010a,b) were also used. The charactersand data matrix used herein (Appendix 1) are from Evans and Reisz(2007) along with four new additional jugal characters identified by Sullivanet al. (2009).

SYSTEMATIC PALEONTOLOGY

DINOSAURIA Owen, 1842ORNITHSCHIA Seeley, 1888

HADROSAURIDAE Cope, 1869LAMBEOSAURINAE Parks, 1923

LAMBEOSAURINI, new tribeLambeosaurini indeterminate

Referred material: SMP VP-2263, nearly complete left humerus(Fig. 1), SMP loc. 403b, De-na-zin Microsite (SE); SMP VP- 1534 (Fig.3), nearly complete right jugal (badly weathered), SMP loc. 392b, De-na-zin Wash (SE).

Horizon and Age: Naashoibito Member (Ojo Alamo Formation),early Maastrichtian.

Description of Humerus: The left humerus (SMP VP-2263) isnearly complete (Fig. 1). In caudal view, the articular (humeral) head andthe proximal edges of the medial side are eroded. Though eroded, thehumeral head constitutes one third of the width of the proximal articularmargin. It bears a complete and prominent deltopectoral crest; its lateralmargin has a strong, well-developed edge for the attachment of the M.deltoideus clavicularis and M. scapulohumeralis rostral (Dilkes, 2000;Evans and Reisz, 2007). The muscle scar of the latissimus dorsi is weaklydeveloped. The degree of angulation of the ventral margin of thedeltopectoral crest is strong (character 221 of Prieto-Márquez, 2010a).In cranial view, the bicipital sulcus is also well-developed and widensproximally, expanding to almost the full width of the element. The caudalsurface of the shaft is damaged, and it is highly fractured in a regionimmediately adjacent to the midpoint of the shaft; however, an accuratereflection of the proportions of the element is not compromised by thisdamage. The radial and ulnar condyles are complete, with the ulnar condyleslightly larger than the radial condyle. The olecranon fossa is well-devel-oped and deeper than the coronoid fossa. Measurements of the humerusare: length = 550 mm; deltopectoral crest length = 260 mm; deltopectoralwidth = 135 mm; width of the shaft = 68 mm. Ratio of deltopectoralwidth to the shaft width = 0.5037. The ratio of the length of the

deltopectoral crest to the proximodistal length of the humerus = 0.47(character 219 of Prieto-Márquez, 2010a). The ratio between the totallength and the width of the lateral surface of the proximal end of thehumerus is 3.6 (character 222 of Prieto-Márquez, 2010a).

Remarks: The robust morphology and measurements of the hu-merus confirm it pertains to a member of the “lambeosaurin” clade basedon a bivariate plot analysis of hadrosaurid taxa, including average mea-surements for hadrosaurid humeri of various genera (Fig. 2). The lengthof the deltopectoral crest of this specimen is more than twice the widthof the humeral shaft, characteristic of a lambeosaurine humerus. Notethat we calculated a ratio of 1.78 for the lateroventral expansion of thedeltopectoral crest of the humerus (character 220 of Prieto-Márquez,2010a), which is nearly the mean for the expanded deltopectoral crest.Thus, SMP VP-2263 lacks the wide deltopectoral crest seen inParasaurolophus, but has a narrower shaft, like Corythosaurus andHypacrosaurus. Shafts of Hypacrosaurus tend to be proportionallylonger than those of Corythosaurus, so we believe that SMP VP-2263 ismore like Corythosaurus than Hypacrosaurus. This specimen also lacksthe rotated orientation of the deltopectoral crest observed in some speci-mens of Hypacrosaurus.

Description of Jugal: SMP VP-1534 (Fig. 3) is a badly weath-ered, but nearly complete, right jugal. Despite its poor condition, enoughof the element is preserved to allow comparison to other hadrosaurines.The jugal has a maximum rostrocaudal length of 255 mm. The shape ofthe jugal conforms to that of lambeosaurines, but it has a morphologythat is inconsistent with jugals of all species of Parasaurolophus (seeSullivan and Bennett, 2000). Specifically, SMP VP-1534 is characterizedby: 1) having an inferior infratemporal border that is wider than theinferior orbital border; 2) lacking a short dorsal caudal process; 3) havinga fan-shaped caudal process border; and 4) lacking the distinctive“W”-shaped articulation between the rostral process of the jugal and thelacrimal, a feature seen only in species of Parasaurolophus. These arenew characters for the jugal (see Appendix 1, below). In addition, in SMPVP-1534 the jugal is also expanded dorsoventrally and forms the lowerpart of the orbital rim; the borders of the infratemporal fenestra form anacute angle between the jugal and postorbital bars; the jugal is dorsoven-trally constricted beneath the infratemporal fenestra; and the ventralflange of the jugal is rounded. The shape of the rostral process is uncer-tain due to breakage.

Remarks: As noted above, based on the characters of the jugal,SMP VP-1534 clearly pertains to a lambeosaurine. Moreover, the lack ofthe distinctive “W”-shaped articulation between the superior border ofthe rostral jugal process, and the inferior border of the lacrimal, indicatesthat the jugal is not from Parasaurolophus. Prieto-Márquez (2010a)identified 13 jugal characters (103 through 115), but only a few can beassessed due to the incomplete nature of SMP VP-1534. These charac-ters include: strong inclination of the bony rim that bounds the medialarticulation surface of the jugal rostral process (character 108 of Prieto-Márquez, 2010a); auricular shape of the quadratojugal flange (character111 of Prieto-Márquez, 2010a); relatively wide and pronounced concav-ity of the ventral margin located between the caudoventral andquadratojugal flanges, despite the fact that the medial section of theventral margin is broken and missing in SMP VP-1534 (character 112 ofPrieto-Márquez, 2010a); and wider orbital margin and relatively con-stricted ventral margin of the infratemporal fenestra (character 112 ofPrieto-Márquez, 2010a).

PHYLOGENETIC ANALYSIS

We scored both the humerus (SMP VP-2263) and jugal (SMP VP-1534) using the data matrix of Evans and Reisz (2007) and added fourmore (new) characters (32-35) identified by Sullivan et al. (2009) for thejugal (see Appendix 1). We ran two analyses: 1) for the jugal; and 2) forthe jugal and humerus combined. The later scenario assumes that the twoelements are from a single taxon. The data analyses were run using PAUP4.0b10 (Swofford, 2002).

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FIGURE 1. Indeterminate lambeosaurin, SMP VP-2263, nearly complete left humerus, from the Naashoibito Member (Ojo Alamo Formation), San JuanBasin, NM. A, caudal view; B, cranial view. Abbreviations: hh, humeral head; ms(lb), muscle scar on the lateral border of the humerus; and ms(ld),muscle scar of the latissimus dorsi. Bar scale = 10 cm.

408

Both analyses produced 470 trees, a tree length of 125, and aconsistency index = 0.8400; retention index = 0.8330 and rescaled con-sistency index = 0.7418. A strict consensus tree and 50% majority-ruleconsensus tree are presented in Figure 4 for both the jugal alone and forthe jugal + humerus combined.

DISCUSSION

Based on our analyses, both SMP VP-1534 and VP-2263 clearlyfall within the Lambeosaurinae and cluster with the Corythosaurus-liketaxa. The strict consensus tree suggests they are distinct from bothLambeosaurus and Parasaurolophus (Fig. 4C), whereas the 50% major-ity rule consensus tree (Fig. 4D) shows both forming a polytomy withCorythosaurus, Velafrons, Olorotitan and Amurosaurus, withLambeosaurus + Hypacrosaurus as a sister group. Based on these analy-ses and our personal observation, we conclude that both these elementsare from a Corythosaurus-like lambeosaurine that appears to be closer toCorythosaurus than to Hypacrosaurus. We consider both to be indeter-minate lambeosaurin [“corythinosaurin”] lambeosaurines.

The presence of a Corythosaurus-like hadrosaur in theNaashoibioto Member, based on these two specimens, reopens the ques-tion of the identity of NMMNH P-19147 (Fig 5). This specimen, whichwas first described by Hunt and Lucas (1991), consists of an incompleteright scapula, parts of both pubes, two dorsal vertebrae, five neuralspines and 22 ribs and/or partial ribs. Williamson (2000) later noted thatthe specimen also included the distal end of the left tibia.

In their taxonomic assessment of this specimen, Hunt and Lucas(1991) noted that the pubes and scapula were the most (potentially)diagnostic elements of this specimen. Unfortunately, the scapula offeredlittle help in actually determining the generic identity of the hadrosaurid.

The right pubis, on the other hand, was complete enough to compare toother hadrosaurids and had features that suggested relationships to knowntaxa. Hunt and Lucas (1981) noted that the right pubis (Fig. 5A, B) wasrelatively short and broad, as in most lambeosaurines. They also notedthat the shape of the scapula was variable in Corythosaurus, so it isinferred that the parallel dorsal and ventral morphology of the scapularblade described by them was considered to be too ambiguous to allow forany taxonomic identification. They concluded that NMMNH P-19147represented a lambeosaurine that was related to either Corythosaurus orLambeosaurus (Hunt and Lucas, 1991).

Williamson (2000, p. 205) reinterpreted NMMNH P-19147, basedon the morphology of the pubis, and stated that “the neck of the pubis isnarrow rather than broad as in lambeosaurines” and that the scapulablade is long with sub-parallel margins, despite the fact that Hunt andLucas (1991) stated that variation in blade morphology is dubious amongCorythosaurus specimens. Williamson (2000) reinterpreted NMMNHP-19147 as a hadrosaurine rather than a lambeosaurine.

A re-evaluation of the morphology of the right pubis (Fig. 5A-B)clearly shows that NMMNH P-19147 is, in fact, a lambeosaurine that isclose to Corythosaurus. Prieto-Márquez (2010a) identified a number ofcharacters of the pubis, most of which we can use to determine theaffinities of NMMNH P-19147. We have presented a reconstruction ofthe prepubic process of the pubis based on the directions of the pre-served dorsal, ventral and cranial margins. Our reconstruction suggeststhat the ventral region is more expanded than the dorsal region (character252 of Prieto-Márquez, 2010a). Despite its broken condition, it is evi-dent that the geometry of the dorsoventral expansion of the prepubicprocess of the pubis of NMMNH P-19147 is oval shaped (Fig. 5B),being dorsoventrally taller than craniocaudally long (character 253 of

FIGURE 2. Bivariate plot of the width of the humeral shafts versus the width of the deltopectoral crest among selected hadrosaurids. Note that SMP VP-2263, falls within the lambeosaurines, having closest affinities to Corythosaurus and Hypacrosaurus.

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FIGURE 3. Indeterminate lambeosaurin, SMP VP-1534, badly weather right jugal, from the Naashoibito Member (Ojo Alamo Formation), San Juan Basin,NM. A, lateral view; B, medial view. Bar scale = 10 cm.

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FIGURE 4. Cladograms. A, strict consensus tree (jugal only); B, 50% majority rule consensus tree (jugal only); C, strict consensus tree (jugal + humerus);D, 50% majority rule consensus tree (jugal + humerus); black dot is the node for the Lambeosaurini The inclusion of Amurosaurus is equivocal based onanalyses of Godefroit (2004, 2008), Evans and Reisz (2007) and Evans (2010). Amurosaurus and Sahaliyania form a clade within Lambeosaurini in theanalysis presented by Prieto-Márquez (2010a, b). The taxon Sahaliyania elunchunorum is considered to be a lambeosaurine, but was not included in ourdata set (see Appendix 2).

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FIGURE 5. NMMNH P-19147, lambeosaurin indeterminate. Incomplete right pubis, A, medial view; B, lateral view. Incomplete right scapula, C, lateralview; D, medial view. Dotted line is the restored prepubic blade based on dorsal, ventral and distal margins of the pubis. Asterisk and black dot indicateposition of maximum concavity for the dorsal and ventral margins (B), after Prieto-Márquez (2010a). Abbreviations: ap, acromion process; p, depthof proximal end of scapula; sb, maximum distal depth of scapula blade; and sn, minimum depth of scapula neck. Bar scales = 10 cm.

412Prieto-Márquez, 2010a). We are unable to determine the ratio betweenthe dorsoventral expansion of the prepubic process relative to the widthof the acetabular margin (character 254 of Prieto-Márquez, 2010a) be-cause the acetabular region in NMMNH P-19147 is largely missing. Thecraniocaudal length of the proximal constriction of the prepubic processis longer than the dorsoventral expansion (character 255 of Prieto-Márquez, 2010a). The relative position of the maximum concavity of thedorsal margin is located distally relative to the point of maximum convex-ity along the ventral margin (character 256 of Prieto-Márquez, 2010a).The morphology of the acetabular margin (character 257 of Prieto-Márquez, 2010a) is unknown because the region is not preserved inNMMNH P-19147. The obturator foramen as well as the iliac and is-chial peduncles (characters 258 through 261 of Prieto-Márquez, 2010a)are also not preserved, so their morphologies and related measurementscannot be assessed. Finally, the total length of the pubis (character 262 ofPrieto-Márquez, 2010a) is not known due to the incomplete nature ofthe pubis.

Our examination of the scapula also confirms that its morphologyis consistent with that of Corythosaurus based on the recent analyses ofPrieto-Márquez (2010a). The dorsal margin of the scapula is curved(character 211 of Prieto-Márquez, 2010a). The ratio of the craniocaudallength and the dorsoventral depth is 5.0, a little less than C. casuariusand C. intermedius (character 212 of Prieto-Márquez, 2010a). Dors-oventral expansion of the distal region (character 213 of Prieto-Márquez,2010a) appears slight, but the scapula’s dorsal and ventral margins arebroken. Nevertheless, we calculated a ratio of 1.0+ for this character thatwould support its lambeosaurine affinities. The ratio between the dors-oventral length of the proximal constriction and the dorsoventral depthof the cranial end of the scapula is 0.75, a value that is nearly the same asthose for Corythosaurus (0.70 to 0.72) (character 214 of Prieto-Márquez,2010a). The acromion process is directed dorsally and is slightly re-curved (characters 215 and 216 of Prieto-Márquez, 2010a). The deltoidridge is weakly developed and is confined to the proximal region of the

scapula (character 218 of Prieto-Márquez, 2010a), a situation similar toHypacrasaurus stebingeri. Therefore, we reject Williamson’s (2000) in-terpretation and conclude that the specimen is a Corythosaurus-likehadrosaurid and is not a hadrosaurine.

BIOSTRATIGRAPHIC SIGNIFICANCE

Hunt and Lucas (1991) considered NMMNH P-19147 to repre-sent a possible range extension for lambeosaurines (Corythosaurus orLambeosaurus) because the Naashoibito Member was considered to belate Maastrichtian age (equivalent to the Lancian) and because there wereno lambeosaurine hadrosaurs known from Lancian age deposits in NorthAmerica. The Naashoibito Member is regarded by us to be pre-Lancian(early Maastrichtian) and has been dated at 69 Ma based on the occur-rence of Alamosaurus sanjuanensis, which is restricted to the NaashoibitoMember in the San Juan Basin (Sullivan and Lucas, 2003, 2006). None-theless, NMMNH P-19147, and the jugal and humerus described above,each from separate localities, are among the youngest knownlambeosaurines (Hypacrosaurus altispinus being the other) in NorthAmerica. More importantly, these specimens may represent the young-est known Corythosaurus-like genus.

ACKNOWLEDGMENTS

We thank Michael Brett-Surman (United States National Mu-seum) for discussions regarding hadrosaurid postcrania. We also thankDavid Evans (Royal Ontario Museum, Toronto) for earlier discussionsregarding lambeosaurines and issues regarding the PAUP analyses. Spe-cial thanks are extended to Peter Dodson (University of Pennsylvania)and Pascal Godefroit (Royal Institute of Natural Sciences of Belgium,Brussels) for their respective critiques and suggestions that improvedthe manuscript. Thanks are extended to the Bureau of Land Managementfor issuing the Paleontological Resource Use permits SMP-8270-RS-01-C and SMP-827 RS-04-D and their continuing support in the field.

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Ogg, J.G., Agterberg, F.P. and Gradstein, F.M., 2004, The Cretaceous Period;in Gradstein, F., Ogg, J., and Smith, A., eds., A Geologic Time Scale:Cambridge, Cambridge University Press, p. 344-383.

Guenther, M.F., 2009, Influence of sequence heterochrony on hadrosauridpostcranial development: The Anatomical Record, v. 292, p. 1427-1441.

Pereda Suberbiola, X., Canudo, J.I., Company, J., Cruzado-Caballero, P.,Barco, J.L. López-Martínez, N., Oms, O. and Ruiz-Omenaca, N., 2009,The last hadrosaurid dinosaurs of Europe: a new lambeosaurine from theuppermost Cretaceous of Aren (Huesca, Spain): Comptes Rendus Palevol,v. 8, p. 559-572.

Prieto-Márquez, A., 2010a, Global phylogeny of Hadrosauridae (Dinosauria:Ornithopoda) using parsimony and Bayesian inference: Zoological Jour-nal of the Linnean Society, v. 159, p. 435-502.

Prieto-Márquez, A., 2010b, Global historical biogeography of hadrosauriddinosaurs: Zoological Journal of the Linnean Society, v. 159, p. 503-525.

Sullivan, R.M. and Bennett, G.E., III, 2000, A juvenile Parasaurolophus(Ornithischia: Hadrosauridae) from the Upper Cretaceous Fruitland For-mation of New Mexico: New Mexico Museum of Natural History andScience, Bulletin 17, p. 215-220.

Sullivan, R.M., Boere, A.C. and Lucas, S.G., 2005a, Redescription of theceratopsid dinosaur Torosaurus utahensis (Gilmore, 1946) and a revi-

sion of the genus: Journal of Paleontology, v. 79, p. 564-582.Sullivan, R.M. and Lucas, S.G., 2003, The Kirtlandian, a new land-verte-

brate "age" for the Late Cretaceous of western North America: NewMexico Geological Society, Guidebook 54, p. 369-377.

Sullivan, R.M. and Lucas, S.G., 2006, The Kirtlandian land-vertebrate"age" - faunal composition, temporal position and biostratigraphic cor-relation in the nonmarine Upper Cretaceous of western North America:New Mexico Museum of Natural History and Science, Bulletin 35, p. 7-29.

Sullivan, R.M., Lucas, S.G. and Braman, D.R., 2005b, Dinosaurs, pollen, andthe Cretaceous-Tertiary boundary in the San Juan Basin, New Mexico:New Mexico Geological Society, Guidebook 56, p. 395-407.

Sullivan, R.M. and Williamson, T.E., 1999, A new skull of Parasaurolophus(Dinosauria: Hadrosauridae) from the Kirtland Formation of New Mexicoand a revision of the genus: New Mexico Museum of Natural Historyand Science, Bulletin 15, 52 p.

Sullivan, R.M., Jasinski, S.E., Lucas, S.G. and Spielmann, J.A., 2009. Thefirst “lambeosaurin” (Dinosauria, Hadrosauridae, Lambeosaurinae) fromthe Upper Cretaceous Ojo Alamo Formation (Naashoibito Member) SanJuan Basin, New Mexico: further implications for the age of the AlamoWash local fauna: Journal of Vertebrate Paleontology, v. 29, p. 188A.

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Williamson, T.E. and Sullivan, R.M., 1998, A new local fauna, the WillowWash local fauna, from the Upper Cretaceous (Campanian), KirtlandFormation, New Mexico: Journal of Vertebrate Paleontology, v. 18, p.86A.

Wiman, C., 1931, Parasaurolophus tubicen n. sp. aus der Kreide in NewMexico: Nova Acta Regiae Societatis Scientiarum Upsaliensis, v. 7, p. 1-11.

APPENDIX 1

Characters and data matrix used in cladistic analysis (modified from Evans and Reisz, 2007).

Skull1. Premaxilla, oral margin with a “double layer” morphology consisting

of an external denticle-bearing layer seen externally and an internalpalatal layer of thickened bone set back slightly from the oral marginand separated from the denticulate layer by a deep sulcus bearingvascular foramina: absent (0); present (1) (Horner et al., 2004, charac-ter 25).

2. Premaxillary rostral bill margin shape: horseshoe-shaped, forms acontinuous semicircle that curves smoothly to postoral constriction(0); broadly arcuate across rostral margin, constricts abruptly behindthe oral margin (1) (Horner et al., 2004, character 22).

3. Premaxillary caudal processes (PM1, PM2) and construction of nasalpassages: caudodorsal premaxillary process short, caudodorsal andcaudoventral processes do not meet caudal to external nares, nasalpassages not enclosed ventrally, external nares exposed in lateral view(0); caudoventral and caudodorsal processes elongate and join behindexternal opening of narial passages to exclude nasals, nasal vestibulecompletely enclosed by tubular premaxillae, left nasal passage di-vided from right passage, homologue of hadrosaurine external narisnot exposed in lateral view (1) (Horner et al., 2004, character 27,modified).

4. Premaxilla, external naris shape: bony external naris formed by pre-maxilla and nasal (0); naris defined entirely by premaxilla, naris elon-gate (1); lacriform in shape, naris constricted caudally, primarily bylateroventral expansion of caudodorsal premaxillary process (2);lacriform in shape, naris constricted caudally primarily by dorsalexpansion of caudolateral premaxillary process (3) (Morris, 1978).

5. Premaxilla, vertical groove on the caudolateral process rostral to themaxillary dorsal process that extends ventrally from a small lateralopening between the premaxillary caudal processes: absent (0); present(1).

6. Premaxilla, elongation of the caudolateral process above the prefron-tal: absent (0); present (1) (Suzuki et al., 2004, character 4, modified).

7. Position of nasal cavity: nasals flat caudodorsally and restricted toarea rostral to braincase, nasal cavity rostromedial to orbits (0); pre-maxilla extended caudally and nasals retracted to lie over braincase inadults, resulting in a convoluted, complex narial passage and hollowcrest that extend supraorbitally (1) (Horner et al., 2004, character 33,modified).

8. Nasal vestibule morphology, s-loop in the enclosed premaxillary pas-sages rostral to dorsal process of maxilla: absent (0); s-loop present(1) (Weishampel, 1981).

4149. Hollow nasal crest tubular, elongate, and extends caudally well beyond

the occiput: absent (0); present (1) (Horner et al., 2004, character 36,in part).

10. Hollow nasal crest shape, solid plate-like extension of premaxilla, or“cockscomb,” above the nasal passages in the rostral region of thecrest (i.e., crest raised into a large vertical fan): absent (0); present (1)(Hopson, 1975; Horner et al., 2004, character 36, in part; Suzuki etal., 2004, character 11).

11. Hollow nasal crest shape, helmet-shaped crest with apex above orbitand nasal forms a large, plate-like portion of the caudal external crestsurface: absent (0); present (1) (Norman, 2002, character 9, modified;Godefroit et al., 2004, character 14, modified).

12. Hollow nasal crest, length: crest absent or extends beyond occiputless than basal skull length (0); extends posterior to occiput morethan basal skull length (1) (Sullivan and Williamson, 1999).

13. Hollow nasal crest, crest-snout angle along dorsal margin of premax-illa in lateral view: absent (0); less than 110 degrees, crest procumbent(1); present, angle between 110 and 155 degrees (2); facial profileshallowly concave in lateral view, angle between 155 and 180 degrees(Suzuki et al., 2004, character 12, modified).

14. Hollow nasal crest, relative shape of the two lobes of caudoventralprocess of premaxilla (PM2): absent (0); present, rostral lobe ap-proximately level with or higher than caudal lobe (1); present, caudallobe higher than rostral lobe (2) (Horner et al., 2004, character 35).

15. Hollow nasal crest, enclosure of the nasal passages on lateral crestsurface between the caudolateral process of the premaxilla and nasal:absent (0); premaxilla nasal-fontanellae persist into late ontogeneticstages (1), crest fontanellae completely closed in subadult individuals(2). (Norman, 2002, character 5, modified).

16. Hollow nasal crest, composition of caudal margin of fan-shapedcrest: absent (0); present, composed of largely of the premaxillacaudodorsal process (PM1), nasal contributes to the lateroventralportion of a solid caudal process only (1); present, composed ofnasal, nasals have long external internasal joint along caudal andcaudoventral margin of crest (2) (Horner et al., 2004, character 37,modified).

17. Hollow nasal crest, rostral nasal-caudodorsal process of premaxilla(PM1) contact: absent (0); present, rostral end of nasal fits alongventral edge of premaxilla (1); present, premaxilla and nasal meet in acomplex W-shaped interfingering suture in which a long, finger-likeprocess of the nasal has an extensive overlapping joint with caudodorsalprocess of the premaxilla in the rostral region of the crest (2) (Horneret al., 2004, character 34, modified).

18. Hollow nasal crest, premaxilla caudodorsal process with accessoryrostroventral flange that overlaps the lateral surface of the nasal in therostral region of the crest: absent (0); present (1) (Evans and Reisz,2007, character 18).

19. Maxilla, rostrodorsal process: has a separate rostral process thatextends medial to the caudoventral process of premaxilla to form partof medial floor of external naris (0); rostral process absent, rostrodorsalmargin of maxilla forms a sloping shelf that underlies the premaxilla(1) (Horner et al., 2004, character 42).

20. Maxilla, dorsal process shape in lateral view: low and gently rounded(0); tall and sharply peaked (1) (Horner et al., 2004, character 48,modified).

21. Maxilla, position of apex in lateral view: well caudal to center (0); ator rostral to center (1) (Horner et al., 2004, character 47).

22. Maxilla, location of large rostral maxillary foramen: opens onrostrolateral body of maxilla, exposed in lateral view (0); opens ondorsal surface of maxilla along maxilla-premaxilla suture (1) (Horneret al., 2004, character 44, modified).

23. Maxilla-lacrimal contact: present externally (0); largely covered ex-ternally by a jugal-premaxilla contact (1) (Horner et al., 2004, charac-

ter 45, modified).24. Maxilla, ectopterygoid ridge: poorly developed (0); strongly devel-

oped, thickened horizontal ridge on lateral surface of maxilla (1)(Godefroit et al., 2004, character 24).

25. Ectopterygoid-jugal contact: present (0); absent, palatine-jugal con-tact enhanced (1) (Horner et al., 2004, character 51).

26. Lacrimal-nasal contact: present (0); absent (1) (Norman, 2002, char-acter 12).

27. Jugal, expansion of rostral end below lacrimal: dorsoventrally nar-row, forms little of the rostral orbital rim (0); expanded dorsoven-trally in front of orbit, lacrimal pushed dorsally to lie completelyabove the level of the maxilla, jugal forms lower portion of orbital rim(1) (Horner et al., 2004, character 52).

28. Jugal, rostral process shape: asymmetrical with a pointed processbetween the maxilla and lacrimal (0); truncated and symmetrical (1)(Horner et al., 2004, characters 53 and 54, modified).

29. Jugal contribution to infratemporal fenestra, acute angle betweenpostorbital bar and jugular bar: absent (0); present (1) (Horner et al.,2004, character 71).

30. Jugal, development of free ventral flange: absent, jugal expands gradu-ally below intrafenestra to meet the quadratojugal-quadrate (0); present,jugal dorsoventrally constricted beneath infratemporal fenestra to setoff flange rostral to constriction (1) (Horner et al., 2004, character55).

31. Jugal, ventral flange shape: rounded or lobate (0); angular (1) (Suzukiet al., 2004, character 21).

32. Jugal, inferior infratemporal border wider then inferior orbit border:present (0); not present (1) (NEW, Sullivan et al., 2009).

33. Jugal, dorsal portion of caudal process shorter then ventral portion ofcaudal process: present (0); not present (1) (NEW, Sullivan et al.,2009).

34. Jugal, border of caudal jugal process fan-shaped rather then sub-rectangular: present (0); not present (1) (NEW, Sullivan et al., 2009).

35. Jugal-lacrimal contact of dorsal border of anterior jugal process “W”-shaped: present (0); not present (1) (NEW, Sullivan et al., 2009).

36. Prefrontal, medial margin forms a thin vertical flange that laps ontothe base of the crest: absent (0); present (1) (Godefroit et al., 2004,character 16).

37. Prefrontal, medial flange extends caudally over the dorsal surface ofthe frontal and above the prefrontal-postorbital joint in lateral view(in adults): absent (0); present (1).

38. Supraorbital articulation: freely articulate on orbit rim (0); fused toorbit rim or absent (1) (Horner et al., 2004, character 59).

39. Postorbital, bifurcation of the caudal process: absent (0); present (1).40. Postorbital, caudal process: elongate above of infratemporal fenestra

(0); short and deep, resulting in a constricted dorsal region of theinfratemporal fenestra (1).

41. Postorbital, dorsal ‘promontorium’: absent (0); present in adults (1)(Godefroit et al., 2004, character 17).

42. Frontal, upward doming over braincase in adults: absent (0); present(1) (Horner et al., 2004, character 58).

43. Frontal, exposed along dorsal margin of orbit: present (0); excludedfrom orbital rim by an extensive prefrontal-postorbital joint (1) (Horneret al., 2004, character 57).

44. Frontal, platform for nasal articulation: absent (0); present, com-prised of two thin, rostroventrally curved tongues that form a mediancleft (1); or thickened and steeply angled, with median cleft absent (2)(Evans and Reisz, 2007, character 40).

45. Frontal, nasal articulation surface extends posterodorsally to over-hang the parietal in adults: absent (0); present (1) (Godefroit et al.,2004, character 4, in part).

46. Frontal, shape of ectocranial surface: elongate with an ectocraniallength/width > 0.8 (0); relatively short, with a length/width < 0.8 (1);

415greatly shortened length/width ratio <0.4) (2) (Godefroit, 2004, char-acter 6, modified).

47. Frontal, shape of the ventral annular ridge that defines the rostralextent of the cerebral fossa: long, low and gently rounded in medialview (0); annular ridge sharp (1) (Evans and Reisz, 2007).

48. Parietal midline crest: straight and level with skull roof or slightlydown-warped along length (0); sagittal crest deepens caudally (stronglydown-warped) (1) (Horner et al., 2004, character 69, modified).

49. Parietal midline crest, length: long, parietal narrows quickly to formthe crest, crest more than half the length of supratemporal fenestrae(0); short, parietal crest narrows gradually caudally, crest less thanhalf the length of the supratemporal fenestrae (1) (Horner et al., 2004,character 70).

50. Parietal, shape: long, length/width ratio greater than 2 (0); less than 2(1) (Godefroit et al., 2004, character 2).

51. Squamosal, separation of squamosals in caudal view: completelyseparated by the parietal (0); extensive intersquamosal joint presentat the midline (1) (Suzuki et al., 2004, character 33, modified).

52. Squamosal, shape of caudoventral surface: shallowly exposed incaudal view (0); form a deep, near vertical, well-exposed face in cau-dal view (1) (Horner et al., 2004, character 64).

53. Squamosal, height above quadrate cotylus: lateral side relatively low(0); markedly expanded dorsally above the cotylus (1) (Godefroit etal., 2004, character 18).

54. Quadrate, shape of mandibular condyle: mediolaterally broad, lateraland medial condyles subequal in size (0); lateral condyle expandedrostrocaudally so that condyles appear subtriangular in distal view,lateral condyle longer than medial one (1) (Horner et al., 2004, charac-ter 60).

55. Laterosphenoid, complete enclosure of ophthalmic sulcus by bonelaterally: absent (0); present (1) (Ostrom, 1961).

56. Supraoccipital, ventral margin: bowed or expanded ventrally alongmidline (0); horizontal, strong ridge developed along supraoccipital-exoccipital suture (1) (Horner et al., 2004, character 30).

57. Transverse width of the cranium in the postorbital region in dorsalview: broad, width maintained from orbit to quadrate head (0); dis-tinctly narrowed at quadrate heads (1) (Horner et al., 2004, character67).

Lower Jaw and Dentition58. Predentary shape: deep and robust, arcuate rostral margin, neurovas-

cular foramina large and located near midline of predentary body,dorsally directed spike-like denticles on rostral margin that fit intoslots on underside of premaxilla (0); gracile and shovel-shaped, straightto gently rounded rostral margin, numerous nutrient foramina acrossentire rostral margin, rounded, triangular denticles project rostrallyand fit into a continuous transverse slot on underside of premaxilla(1) (Horner et al., 2004, character 13, modified).

59. Dentary, orientation of ramus rostral to tooth row in lateral view:approximately straight or moderately down-turned (0); or stronglydeflected (1) (Horner et al., 2004, character 11, modified).

60. Dentary, coronoid process inclination: oriented roughly perpendicu-lar to the dentary ramus (0); inclined rostrally (1) (Suzuki et al., 2004,character 39).

61. Coronoid process configuration: apex only slightly expanded ros-trally, surangular large and forms much of caudal margin of coronoidprocess (0); dentary forms nearly all of greatly rostrocaudally ex-panded apex, surangular reduced to thin sliver along caudal marginand does not reach to the distal end of the coronoid process (1)(Horner et al., 2004, character 17).

62. Dentary, length of diastema between first dentary tooth andpredentary: short, less than one-fifth the length of the tooth row (0);long, greater than one-fifth of the length of the tooth row (1) (Horner

et al., 2004, character 9, modified).63. Dentary, number of replacement teeth per position: two or less (0);

three or more (1) (Horner et al., 2004, character 2).64. Dentition, number of tooth rows: 32 or less (0); greater than 32 (1)

(Horner et al. 2004, character 1; Suzuki et al., 2004, character 46,modified).

65. Dentary crown shape (middle of tooth row): diamond-shaped with aheight/width ratio less than 3.0 (0); elongate lanceolate-shaped with aheight/width ratio greater than 3.1 (1) (Horner et al., 2004, character5, modified).

66. Dentary teeth, number of accessory ridges: two or more prominentridges (0); tooth crown dominated by one primary ridge, secondaryridges are faint when present (1) (Godefroit et al., 2004, character30).

67. Dentary teeth, position of apex: offset to either mesial or distal side,or some teeth curved distally (0); apex central, tooth straight andnearly symmetrical (1) (Horner et al., 2004, character 8, modified).

68. Surangular foramen: present (0); absent (1) (Horner et al., 2004,character 19).

69. Angular, position on lower jaw: large and deep, exposed laterally (0);dorsoventrally narrow and not visible in lateral view (1) (Weishampelet al., 1993, character 26).

Postcranial Skeleton70. Cervical vertebrae, number: 13 or fewer (0); greater than 13 (1)

(Horner et al., 2004, character 72, modified).71. Mid-dorsal vertebrae (~D10), neural spine height greater than 4 times

centrum height: absent (0); present (1) (Suzuki et al., 2004, character51, modified).

72. Dorsal (caudal) and sacral neural spines: short, less than three timescentrum height (0); elongate, approximately three times centrum heightor greater (1) (Horner et al., 2004, character 76, modified).

73. Sacrum, number of sacral vertebrae: seven or fewer (0), eight or more(1) (Horner et al., 2005, character 75).

74. Scapula, shape of proximal end: dorsoventrally deep, acromion pro-cess directed dorsally, articulation extensive (0); dorsoventrally nar-row (no wider than distal scapula), acromion process projects hori-zontally, cranioventral corner notched, articulation restricted (1)(Horner et al., 2004, character 80).

75. Scapula, dorsal border: straight (0); curved rostroventrally (1)(Norman, 2002, character 43).

76. Scapula, orientation of borders of distal blade: divergent (0); subparallelto one another (1) (Horner et al., 2005, character 81).

77. Coracoid, biceps tubercle size: tubercle small (0); large, laterallyprojecting biceps tubercle (1) (Horner et al., 2004, character 78, modi-fied).

78. Coracoid, cranioventral process (cranioventral hook): short and weaklydeveloped (0); long, extends well below the glenoid (1) (Horner et al.,2004, character 79).

79. Coracoid size: large, coracoid: scapula lengths more than 0.2, lengthof articular surface greater than length of glenoid (0); coracoid reducedin length relative to scapula, glenoid equal to or longer than articula-tion (1) (Horner et al., 2004, character 77, modified).

80. Humerus, deltopectoral crest length: short, much less than half thelength of the humerus (0); extends at least to midshaft or longer (1)(Horner et al., 2004, character 83).

81. Humerus, deltopectoral crest shape: relatively low (0); angular andenlarged (1) (Suzuki et al., 2004, character 59, modified).

82. Humeral distal condyles: compressed mediolaterally, flares little fromshaft of humerus (0); mediolaterally broad, flare moderately fromshaft of humerus (1) (Horner et al., 2004, character 84, modified).

83. Antebrachium length: humerus subequal to or longer than radius (0);radius significantly longer than humerus (1) (Horner et al., 2004,character 85).

41684. Carpus: robust, with more than two small bones present and proxi-

mal ends of the metacarpals aligned (0); reduced to no more than twosmall carpals with MCIII offset distally with respect to MCII and IV(1) (Horner et al., 2004, characters 86 and 88, modified; Suzuki et al.,2004, character 57, modified).

85. Manus, digit 1: metacarpal and one phalanx present (0); entire digitabsent (1) (Horner et al., 2004, character 87).

86. Manus, Digit III-1: longer than wide (0); as wide or wider than long(1) (Suzuki et al., 2004, character 66, modified).

87. Ilium, size of supracetabular process: small, projects only as a lateralswelling (0); large, broadly overhangs the lateral side of the ilium andusually extends at least half way down the side of ilium (1) (Horner etal., 2004, character 91).

88. Ilium, shape of dorsal margin: nearly straight (0); distinctly depressedover supracetabular process and dorsally bowed over base ofpreacetabular process (1) (Horner et al., 2004, character 100).

89. Ilium, postacetabular process: short and triangular in lateral viewwith a large brevis shelf (0); rectangular in outline, brevis shelf absent(1) (Horner et al., 2004, character 93).

90. Pubis, iliac peduncle: relatively small (0); has the form of a large anddorsally directed process (1) (Horner et al., 2004, character 92, modi-fied).

91. Pubis, height of prepubic process: maximum depth of prepubic bladeless than twice the height the minimum constriction (0); expanded,

greater than twice height of minimum constriction (1) (Horner et al.,2004, character 95, modified).

92. Pubis, length of prepubic process constriction: long, dorsoventralexpansion restricted to distal process (0); shaft short, dorsoventralexpansion begins at base of process, repubic neck relatively tall (1)(Horner et al., 2004, character 96, modified).

93. Ischium, shape of distal end: small knoblike foot (0); large and pen-dent foot (1) (Horner et al., 2004, character 99).

94. Ischium, expansion of terminal foot: less than 25 percent the lengthof the ischium (0); greater than 25 percent the ischium length (1)(Suzuki et al., 2004, character 73, modified).

95. Femur, development of intercondylar extensor groove: moderatelydeep, groove fully open (0); deep, edges of groove meet or nearlymeet cranially to enclose an extensor tunnel (1) (Horner et al., 2004,character 101).

96. Tarsus, modified with cranial ascending process of astragalus equilat-eral in shape and expanded distal fibular head: absent (0); present (1)(Godefroit et al., 2004, characters 39 and 40).

97. Pes, distal phalanges of pedal digits II through IV: axially shortenedto disclike elements with width at least three times length (0); greatlyshortened, width at least four times length (1) (Horner et al., 2004,character 104).

98. Pes, shape of unguals: taper evenly distally, clawlike (0); dorsoven-trally flattened and broadened, hoof-like (1) (Horner et al., 2004,character 105).

APPENDIX 2

SYSTEMATIC PALEONTOLOGY

FAMILY HadrosauridaeSUBFAMILY Lambeosaurinae

TRIBE Lambeosaurini, new tribe

Type species: Lambeosaurus lambei Parks, 1923.Included species (following Evans and Reisz [2007] and with

the additional characters included herein): Corythosaurus casuarius,Hypacrosaurus altispinus, Hypacrosaurus stebingeri, Lambeosauruslambei, Lambeosaurus magnicristatus, Olorotitan arharensis, andVelafrons coahuilensis.

Equivocal taxa: Amurosaurus riabinini and Sahaliyaniaelunchunorum (see Prieto-Márquez, 2010a, b).

Diagnosis: Lambeosaurines distinguished from parasaurolophinesby the following features: premaxilla has a vertical groove on thecaudolateral process rostral to the maxillary dorsal process that extendsvertically from a small lateral opening between the premaxillary caudalprocesses; nasal vestibule morphology consists of an S-loop in the en-closed premaxillary passages rostral to the dorsal process of the maxilla;and 13 or fewer cervical vertebrae present (characters 5, 8, and 66, re-spectively, of Evans and Reisz, 2007).

Comments: Previously the Lambeosaurini consisted of four gen-era: Lambeosaurus, Corythosaurus, Hypacrosaurus, and Nipponosaurus;but later the clade was revised to include Olorotitan (Evans et al., 2007).Recent work by Prieto-Márquez (2010a, b) included the following taxain this clade: (1) Corythosaurus intermedius, which we consider to be asubjective junior synonym of C. casuarius, and (2) ?Lambeosaurus

417laticaudus, a taxon that has been recognized as having a suite of charac-ters similar to those of Hypacrosaurus stebingeri (see Evans and Reisz,2007), but as currently recognized, is paraphyletic to both Lambeosaurusand Hypacrosaurus, based on the recent phylogenetic analyses pre-sented by Prieto-Márquez (2010a, b). His analysis suggests that “H.”stebingeri belongs to a genus other than Hypacrosaurus or Lambeosaurusas “H.” stebingeri is nested within the “corythosaurs” (which includesLambeosaurus) whereas ?L. laticaudus is nested within the“hypacrosaurs,” but it is excluded from the “corythosaur” clade, whichincludes Lambeosaurus (see Prieto-Márquez, 2010a, b). A recent studyof Hypacrosaurus stebingeri (Brink et al., 2010) concluded that it wasmore closely related to Corythosaurus than to Lambeosaurus, whileanother study (Evans, 2010) concluded that H. stebingeri is a metaspeciesand that it may be the ancestor of H. altispinus. Godefroit (2004, 2008),Evans and Reisz (2007) and Evans (2010) considered Amurosaurusrabinini to be a basal lambeosaurine. However, our analysis Amurosaurusforms a polytomy with Olorotitan, Corythosaurus, Velafrons and thejugal and humerus specimens (SMP VP-1534 and VP-2263, resectively).The newly named taxon Sahaliyania elunchunorum formed a polytomywith the Lambeosaurini and Parasaurolophini based on the phyloge-netic analysis presented by Godefroit et al. (2008, fig. 18), yet it is

nested within the “hypacrosaur” clade ((Sahaliyania + Amurosaurus)(Hypacrosaurus (Lambeosaurus + Velafrons))) according to Prieto-Márquez (2010a, b). Velafrons coahuilensis was part of the polytomiclambeosaurin clade recognized by Gates et al. (2007). Both Sahaliyaniaand Velafrons are herein included in our modified data set of Evans andReisz (2007) and are considered to be lambeosaurins. We note thatCharonosaurus jiayinensis fell well outside the Lambeosaurini in themodified analysis of Evans and Reisz (2007), which is contrary to itsposition in the analyses of Prieto-Márquez (2010a, b). Nipponosaurussachalinensis was omitted by Prieto-Márquez (2010a, b) but it wasincluded in the definition of the clade and analysis of Evans and Reisz(2007) despite the fact that the taxon is based on a juvenile and incom-plete individual. Evans and Reisz (2007) noted that the topology of theircladogram did not change with the omission of Nipponosaurus. There-fore, following Prieto-Márquez (2010a, b) we do not recognize Nippono-saurus as belonging to the Lambeosaurini. Our definition of theLambeosaurini would be equivalent to node 38 of Prieto-Márquez (2010a:fig. 9), with the exception that we include Olorotitan, which may beequivocal. The taxa Amurosaurus riabinini and Sahaliyania elunchunorumare members of the Lambeosaurini based on the recent analysis of Prieto-Márquez (2010a, b), but their phylogenetic position is equivocal basedon the analysis of Evans and Reisz (2007) and Evans (2010).